netdev - Re: [PATCH net-next RFC] virtio_net: ethtool tx napi configuration

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Date:   Thu, 13 Sep 2018 17:13:29 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        netdev@...r.kernel.org
Cc:     mst@...hat.com, f.fainelli@...il.com,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next RFC] virtio_net: ethtool tx napi configuration



On 2018年09月13日 07:29, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
>
> Implement ethtool .set_priv_flags and .get_priv_flags handlers
> and use ethtool private flags to toggle transmit napi:
>
>    ethtool --set-priv-flags eth0 tx-napi on
>    ethtool --show-priv-flags eth0
>
> Link: https://patchwork.ozlabs.org/patch/948149/
> Suggested-by: Jason Wang <jasowang@...hat.com>
> Suggested-by: Florian Fainelli <f.fainelli@...il.com>
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> ---
>   drivers/net/virtio_net.c | 49 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 49 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 765920905226..9ca7e0a0f0d9 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -73,6 +73,10 @@ static const unsigned long guest_offloads[] = {
>   	VIRTIO_NET_F_GUEST_UFO
>   };
>   
> +static const char virtnet_ethtool_priv_flags[][ETH_GSTRING_LEN] = {
> +	"tx-napi",
> +};
> +
>   struct virtnet_stat_desc {
>   	char desc[ETH_GSTRING_LEN];
>   	size_t offset;
> @@ -2059,6 +2063,9 @@ static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)
>   			}
>   		}
>   		break;
> +	case ETH_SS_PRIV_FLAGS:
> +		memcpy(data, virtnet_ethtool_priv_flags,
> +		       sizeof(virtnet_ethtool_priv_flags));
>   	}
>   }
>   
> @@ -2070,6 +2077,9 @@ static int virtnet_get_sset_count(struct net_device *dev, int sset)
>   	case ETH_SS_STATS:
>   		return vi->curr_queue_pairs * (VIRTNET_RQ_STATS_LEN +
>   					       VIRTNET_SQ_STATS_LEN);
> +	case ETH_SS_PRIV_FLAGS:
> +		return ARRAY_SIZE(virtnet_ethtool_priv_flags);
> +
>   	default:
>   		return -EOPNOTSUPP;
>   	}
> @@ -2181,6 +2191,43 @@ static int virtnet_get_link_ksettings(struct net_device *dev,
>   	return 0;
>   }
>   
> +static int virtnet_set_priv_flags(struct net_device *dev, u32 priv_flags)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +	int i, napi_weight;
> +
> +	napi_weight = priv_flags & 0x1 ? NAPI_POLL_WEIGHT : 0;
> +
> +	if (napi_weight ^ vi->sq[0].napi.weight) {
> +		for (i = 0; i < vi->max_queue_pairs; i++) {
> +			struct netdev_queue *txq =
> +				netdev_get_tx_queue(vi->dev, i);
> +
> +			virtnet_napi_tx_disable(&vi->sq[i].napi);
> +			__netif_tx_lock_bh(txq);
> +			vi->sq[i].napi.weight = napi_weight;
> +			if (!napi_weight)
> +				virtqueue_enable_cb(vi->sq[i].vq);

I don't get why we need to disable enable cb here.

Thanks

> +			__netif_tx_unlock_bh(txq);
> +			virtnet_napi_tx_enable(vi, vi->sq[i].vq,
> +					       &vi->sq[i].napi);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static u32 virtnet_get_priv_flags(struct net_device *dev)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +	int priv_flags = 0;
> +
> +	if (vi->sq[0].napi.weight)
> +		priv_flags |= 0x1;
> +
> +	return priv_flags;
> +}
> +
>   static void virtnet_init_settings(struct net_device *dev)
>   {
>   	struct virtnet_info *vi = netdev_priv(dev);
> @@ -2219,6 +2266,8 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
>   	.get_ts_info = ethtool_op_get_ts_info,
>   	.get_link_ksettings = virtnet_get_link_ksettings,
>   	.set_link_ksettings = virtnet_set_link_ksettings,
> +	.set_priv_flags = virtnet_set_priv_flags,
> +	.get_priv_flags = virtnet_get_priv_flags,
>   };
>   
>   static void virtnet_freeze_down(struct virtio_device *vdev)